Method of preventing oxidation of formaldehyde and product thereof.



UNITED STATES PATENT OFFICE.

LUDWIG H. REUTER, OF NEW YORK, N. Y.

METHOD OF PREVENTING OXIDATION OF FORMALDEHYDE AND PRODUCT THEREOF.

Specification of Letters Patent.

Patented May 14.1907.

Application filed July 19, 1906. Serial No. 326,867-

'To all whom it may concern:

Be it known that I, LUDwIe H. REUTER, a citizen of the United States, residing at New York, borough of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Method of Preventing Oxidation of Formaldehyde and Product Thereof, of which the following is a specification.

My invention relates to a method of pre venting the oxidation of formaldehyde in solution and the formation of formic acid therein, and to the products to be obtained by carrying out said method.

While the method is capable of general application in all solutions of formaldehyde gas and of paraformaldehyde and trioxymethylen it is especially valuable in its application to formaldehyde soap solutions.

It is known that the commercial 40% formaldehyde solution continuously oxidizes to produce formic acid, and that formaldehyde solutions containing formic acid, develop such irritating effects that they cannot be used in their ordinary condition as antiseptics, for example, for dressing wounds. Now I have carried onextensive investigations, not only for the purpose of finding a proper method of preparing formaldehyde solutions free from formic acid, but I also have made an extensive series of experiments for the purpose of finding a method of preventing further formation of formic acid in the finished preparation, especially in liquid formaldehyde soaps. Now while it is known that ordinary aqueous solutions of formaldehyde are continuouslyoxidized, I have discovered that also in formaldehyde soaps such an oxidation takes place and that a steady decrease of the formaldehyde contents takes place involving secondary decompositions. In soaps containing 20 per cent and more of formaldehyde gas a quantity of formic acid is formed, which is almost proportionate to the amount of formic acid procured in weaker preparations containing I only up to 10 per cent of formaldehyde gas.

While I have found that in various samples of the weakersoap preparations, containing in the whole body of soap up to 10 per cent of formaldehyde gas, 0.18-0.21 -0.230.26

cent 0 formic acid in the whole body of soap had been formed within about two years, the samples containing 20 per cent of formaldehyde gas were found to contain 0.45

'0.28-fper cent or on the average 0.232 per 0.49O.52 0.64 and 0.66 per cent or in the average 0.552 per cent of formic acid. These results show that in the weaker solutions, containing up to 10 per cent gas, about 0.0232 parts by weight of formic acid were formed for each part of formaldehyde gas, viz.: that within two years 2.3 per cent of original formaldehyde had been converted into formic acid, while in the stronger (20 per cent) soaps 0.0276 of formic acid had been formed for each (part of formaldehyde, equiv.- alent to an oxi ation of 2.8 per cent of the original formaldehyde.

Now I have discovered that certain neutral salts of sulfurous acid, when added to formaldehyde solutions containing either formaldehyde gas or other formaldehyde preparations or derivatives, prevent the further formation of formic acid. These salts are the sulfites of the alkali metals, sodium, otassium, lithium, caesium, and rubidium. n certain samples of formaldehyde liquid soap, even if kept under unfavorable conditions, such for example, as in white partly filled bottles with the sulfite added, only a part of the sulfite has been converted into sulfate in about two years owing to the combined oxidizing influence of light and air.

Quantitative determinations of samples, prepared about two years ago, show conclusively that the amount of sulfate, formed by oxidation of the sulfite, is proportionate to the amount of formic acid formed in other sam les, to which no sulfite had been added at t e time of preparing all these samples. These results show that such sulfites can be used with great advantage to keep formaldehyde from becoming oxidized into formic acid and that at first only the sulfite will be oxidized without impairing in the least the strength or e'fliciency of the formaldehyde contents.

While one part by weight of oxygen oxidizes 1.875 parts of formaldehyde, forming 2.875 parts of formic acid, one part of oxygen is required to oxidize 8 parts of the pure 98% sodium sulfite of the market into sodium sulfate:

1) CHOH O HO0.0H 2) Na SO O Na SO or, it takes one molecule of sulfite to prevent the formation of one molecule of formic acid.

Indeed I have found that the formation of formic acid can be prevented by the addition of about 0.07 parts by weight of sodium sulfite for each part of formaldehyde, and I have found that it takes almost two years until i that amount of sulfite is oxidized even under unfavorable conditions of keeping. This discovery is of great importance as 1t makes it possible not only to ship a liquid formaldehyde soap or other solution over great distances to foreign countries, but also to keep w to 0.7 per cent of dry, preferab y anhydrous,

sodium sulfite, reviously dissolved in water, or to a liquid formaldehyde soap, containing from 20 to 50 per cent of formaldehyde gas, 1.5 to 3.75 per cent of such sulfite,

' previously dissolved 1n water.

I do not Wish to limit myself to the use of dry anhydrous sodium sulfite, as also the proportionate quantity of the crystallized saltNa SO +7H Ocan be used; in this case instead of each part of the dry salt about two parts of the crystallized salt are required.

Instead of sodium sulfite also the proportionate quantity of other alkali metal sul-' fites, can be used,.as for exam le, potassium sulfite (K 80 dry or crystal ized.v I have found that the use of the potassium salts is preferable in combination with those formaldehyde soaps', which contain a mixture of potassium leates and potassium palmitate.

I have discovered also that the oxidation of formaldehyde is about one-third larger if the soap contains free alkali; for formaldehyde soaps containing free alkali, consequently, the addition of more sulfite is required and I have found that it is necessary to add to such liquid, alkaline, formaldehyde soaps for each part of formaldehydeinstead of 0.07 parts-at least 0.1 parts of dry 50- dium sulfite, or of the proportionate quantity of the crystallized sodium sulfite, or of the dry or or stallized potassium sulfite.

To liquid ormaldehyde soaps, containing 2050 per cent of formaldehyde gas, which are intended especially for disinfecting purposes and which may have to be shipped over a long distance or to be StOi'Ck. for along time, for instance, for military purposes 1n tropical countries, I add instead of"1.53.75

per cent or more'of the sulfite.

While I have describ d my method as ap-' plied to' certain particular compositions andstated the exact nature of the products thereof, I am aware that many modifications may be made in the application of the invention to provide for its use with other formaldehyde preparations than those mentioned, therefore, I do not wish to be limited to the exact pro ortions and ingredients specified by way 0 example, but

' What I do claim and desire tosecure by Letters Patent is r v 1. A method of preventing the oxidation of formaldehyde in soap solutionwhich consists in adding to the solution a neutral sulfite of an alkali metal'.- 1 7 2. A method of preventing the oxidation of formaldehyde in a liquid formaldehyde soap solution which consists in adding sodium sulfite to the solution.

3. A method of preventing om'dation of formaldehyde in a liquid formaldehyde soap solution which consists in adding substantially .07 parts by weight of sodium sulfite previously dissolved in water to each part of formaldehyde contained in the soap.

4. A solution comprising soap formaldehyde, and a neutral sulfite of an alkali metal.

5. A solution comprising soapformaldehyde and neutral sodium sulfite, such solution being free from formic acid.

6. A solution containing soap, formaldehyde and sodium sulfite.

7. A solution containing soa formaldehyde and substantially .07 parts y weight of sodium sulfite tOiGtlOh part of formaldehyde in the solution.

8. A solution comprising soa free formaldehyde, and a free neutral s te of an alkali metal. V

In testimony whereof I have hereunto set my hand, in the presence of two subscribing witnesses.

LUDWIG H. REUTER.

Witnesses: V JOHN J. HENNEBERGER, MARY V. DONLAN. 

